Past and future direct radiative forcing of nitrate aerosol in East Asia

Li, Jiandong; Wang, Wei‐Chyung; Liao, Hong; Chang, Wenyuan

doi:10.1007/s00704-014-1249-1

Cited by 25 publications

(30 citation statements)

References 47 publications

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“…Uncertainties in these estimates reflect poorly bounded emission magnitudes including for cooling versus warming agents and naturally arising climate variability, and are largest for household fossil fuel and biofuel, off-road (land) transportation, shipping, biomass burning, and agricultural waste burning. Figure 1), consistent with more recent estimates (e.g., Li et al, 2014;Heald et al, 2014;Zelinka et al, 2014). Sulfate also plays a dominant role in anthropogenic aerosol-cloud interactions (Takemura et al, 2012;Shindell et al, 2013).…”

Section: Semi-directsupporting

confidence: 80%

Air Quality and Climate Connections

Fiore

Naik

Leibensperger

2015

Journal of the Air & Waste Management Association

402

292

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Multiple linkages connect air quality and climate change. Many air pollutant sources also emit carbon dioxide (CO 2 ), the dominant anthropogenic greenhouse gas (GHG). The two main contributors to non-attainment of U.S. ambient air quality standards, ozone (O 3 ) and particulate matter (PM), interact with radiation, forcing climate change. PM warms by absorbing sunlight (e.g., black carbon) or cools by scattering sunlight (e.g., sulfates) and interacts with clouds; these radiative and microphysical interactions can induce changes in precipitation and regional circulation patterns. Climate change is expected to degrade air quality in many polluted regions by changing air pollution meteorology (ventilation and dilution), precipitation and other removal processes, and by triggering some amplifying responses in atmospheric chemistry and in anthropogenic and natural sources. Together, these processes shape distributions and extreme episodes of O 3 and PM. Global modeling indicates that as air pollution programs reduce SO 2 to meet health and other air quality goals, near-term warming accelerates due to "unmasking" of warming induced by rising CO 2 . Air pollutant controls on CH 4 , a potent GHG and precursor to global O 3 levels, and on sources with high black carbon (BC) to organic carbon (OC) ratios could offset near-term warming induced by SO 2 emission reductions, while reducing global background O 3 and regionally high levels of PM. Lowering peak warming requires decreasing atmospheric CO 2 , which for some source categories would also reduce co-emitted air pollutants or their precursors. Model projections for alternative climate and air quality scenarios indicate a wide range for U.S. surface O 3 and fine PM, although regional projections may be confounded by interannual to decadal natural climate variability. Continued implementation of U.S. NO x emission controls guards against rising pollution levels triggered either by climate change or by global emission growth. Improved accuracy and trends in emission inventories are critical for accountability analyses of historical and projected air pollution and climate mitigation policies.Implications: The expansion of U.S. air pollution policy to protect climate provides an opportunity for joint mitigation, with CH 4 a prime target. BC reductions in developing nations would lower the global health burden, and for BC-rich sources (e.g., diesel) may lessen warming. Controls on these emissions could offset near-term warming induced by health-motivated reductions of sulfate (cooling). Wildfires, dust, and other natural PM and O 3 sources may increase with climate warming, posing challenges to implementing and attaining air quality standards. Accountability analyses for recent and projected air pollution and climate control strategies should underpin estimated benefits and trade-offs of future policies.

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Section: Semi-directsupporting

confidence: 80%

Air Quality and Climate Connections

Fiore

Naik

Leibensperger

2015

Journal of the Air & Waste Management Association

402

292

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“…The gas absorptions in the atmosphere were set to constant. The scattering aerosol SSA was set to 0.9999 (similar to that of sulfate or nitrate, Li et al, 2015b) when calculating its DRF. The DRF of the absorbing aerosols is derived from the differences between the total and scattering aerosol DRFs.…”

Section: Methodologies Sampling Station and Instrumentsmentioning

confidence: 99%

“…Due to a lack of SSA ob- servations of each aerosol component, the scattering aerosol DRF is estimated based on a given SSA value (0.9999, equal to that of sulfate or nitrate aerosol) in a reference (Li et al, 2015b). As indicated in the last section, the absorbing aerosols in urNJ are always in a mixed state.…”

Section: The Direct Radiative Forcing Of the Aerosolsmentioning

confidence: 99%

“…Here, this value is derived from the difference between the total and scattering aerosol DRFs, which might be more representative. For comparison, the aerosol DRF is also calculated based on the AAODs, AAEs and BC SSA (Li et al, 2015b).…”

Section: The Direct Radiative Forcing Of the Aerosolsmentioning

confidence: 99%

“…For further comparisons (Fig. 13), the absorbing aerosol DRFs based on the observed AAOD, AAE and fresh BC SSA (Li et al, 2015b) are also used. Although the absorbing aerosol DRFs are estimated in different ways, they are highly correlated at both the TOA and surface, as shown in the figure.…”

Section: The Aerosol Direct Radiative Forcing In Clear-sky Conditionsmentioning

confidence: 99%

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The optical properties, physical properties and direct radiative forcing of urban columnar aerosols in the Yangtze River Delta, China

et al. 2018

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Abstract. The optical and physical properties as well as the direct radiative forcings (DRFs) of fractionated aerosols in the urban area of the western Yangtze River Delta (YRD) are investigated with measurements from a Cimel sun photometer combined with a radiation transfer model. Ground-based observations of aerosols have much higher temporal resolutions than satellite retrievals. An initial analysis reveals the characteristics of the optical properties of different types of fractionated aerosols in the western YRD. The total aerosols, mostly composed of scattering components (93.8 %), have mean optical depths of 0.65 at 550 nm and refractive index of 1.44 + 0.0084i at 440 nm. The fine aerosols are approximately four times more abundant and have very different compositions from coarse aerosols. The absorbing components account for only ∼ 4.6 % of fine aerosols and 15.5 % of coarse aerosols and have smaller sizes than the scattering aerosols within the same mode. Therefore, fine particles have stronger scattering than coarse ones, simultaneously reflecting the different size distributions between the absorbing and scattering aerosols. The relationships among the optical properties quantify the aerosol mixing and imply that approximately 15 and 27.5 % of the total occurrences result in dustand black-carbon-dominating mixing aerosols, respectively, in the western YRD. Unlike the optical properties, the size distributions of aerosols in the western YRD are similar to those found at other sites over eastern China on a climatological scale, peaking at radii of 0.148 and 2.94 µm. However, further analysis reveals that the coarse-dominated particles can also lead to severe haze pollution over the YRD. Observation-based estimations indicate that both fine and coarse aerosols in the western YRD exert negative DRFs, and this is especially true for fine aerosols (−11.17 W m −2 at the top of atmosphere, TOA). A higher absorption fraction leads directly to the negative DRF being further offset for coarse aerosols (−0.33 W m −2 ) at the TOA. Similarly, the coarsemode DRF contributes to only 13.3 % of the total scattering aerosols but > 33.7 % to the total absorbing aerosols. A sensitivity analysis states that aerosol DRFs are not highly sensitive to their profiles in clear-sky conditions. Most of the aerosol properties and DRFs have substantial seasonality in the western YRD. The results further reveal the contributions of each component of the different size particles to the total aerosol optical depths (AODs) and DRFs. Additionally, these results can be used to improve aerosol modelling performance and the modelling of aerosol effects in the eastern regions of China.

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Implications of RCP emissions on future PM_2.5 air quality and direct radiative forcing over China

Liao

Zhu

et al. 2016

JGR Atmospheres

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Severe PM2.5 air pollution in China and the First Grand National Standard (FGNS), implemented in 2016 (annual PM2.5 concentration target of less than 35 µg m−3), necessitate urgent reduction strategies. This study applied the nested‐grid version of the Goddard Earth Observing System (GEOS) chemical transport model (GEOS‐Chem) to quantify 2000–2050 changes in PM2.5 air quality and related direct radiative forcing (DRF) in China, based on future emission changes under the representative concentration pathway (RCP) scenarios of RCP2.6, RCP4.5, RCP6.0, and RCP8.5. In the near term (2000–2030), a projected maximum increase in PM2.5 concentrations of 10–15 µg m−3 is found over east China under RCP6.0 and RCP8.5 and less than 5 µg m−3 under RCP2.6 and RCP4.5. In the long term (2000–2050), PM2.5 pollution clearly improves, and the largest decrease in PM2.5 concentrations of 15–30 µg m−3 is over east China under all RCPs except RCP6.0. Focusing particularly on highly polluted regions, we find that Beijing‐Tianjin‐Hebei (BTH) wintertime PM2.5 concentrations meeting the FGNS occur after 2040 under RCP2.6, RCP4.5, and RCP8.5, and summertime PM2.5 concentrations reach this goal by 2030 under RCP2.6 and RCP4.5. In Sichuan Basin (SCB), wintertime PM2.5 concentrations below the FGNS occur only in 2050 under RCP2.6 and RCP4.5, although future summertime PM2.5 will be well controlled. The difficulty in controlling future PM2.5 concentrations relates to unmitigated high levels of nitrate, although NOx and SO2 emissions show substantial reductions during 2020–2040. The changes in aerosol concentrations lead to positive aerosol DRF over east China (20°–45°N, 100°–125°E) by 1.22, 1.88, and 0.66 W m−2 in 2050 relative to 2000 under RCP2.6, RCP4.5, and RCP8.5, respectively. When considering both health and climate effects of PM2.5 over China, for example, PM2.5 concentrations averaged over east China under RCP4.5 (RCP2.6) decrease by 54% (43%) in 2050 relative to 2000, but at the cost of warming with DRF of 1.88 (1.22) W m−2. Our results indicate that it will be possible to mitigate future PM2.5 pollution in China, but it will likely take two decades for polluted regions such as BTH and SCB to meet the FGNS, based on all RCP scenarios. At the same time, the consequent warming effects from reduced aerosols are also significant and inevitable.

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Past and future direct radiative forcing of nitrate aerosol in East Asia

Cited by 25 publications

References 47 publications

Air Quality and Climate Connections

Air Quality and Climate Connections

The optical properties, physical properties and direct radiative forcing of urban columnar aerosols in the Yangtze River Delta, China

Implications of RCP emissions on future PM_2.5 air quality and direct radiative forcing over China

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Past and future direct radiative forcing of nitrate aerosol in East Asia

Cited by 25 publications

References 47 publications

Air Quality and Climate Connections

Air Quality and Climate Connections

The optical properties, physical properties and direct radiative forcing of urban columnar aerosols in the Yangtze River Delta, China

Implications of RCP emissions on future PM2.5 air quality and direct radiative forcing over China

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Product

Resources

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Implications of RCP emissions on future PM_2.5 air quality and direct radiative forcing over China